I feel bad getting rid of things that are still usable/functional or in good condition, I feel guilty disposing of things that were presents (regardless of whether I like or dislike the item in question)

Oh gosh, me toooooo. Even if I do not use the usable things, or they are only barely usable. One of the things I am trying to get rid of now is perfectly usable, relatively new $clothes that I just don't find comfortable. It is hard.